Cam mechanism for variable length throw



Jan. 3, 1950 H. RANNEY ET AL CAM MECHANISM FOR VARIABLE LENGTH THROW 2Sheets-Sheet 1 Filed Feb. 18, 1948 & 2! zz if WWW W 7% if 1323a ffdaiiw2 SheetsSheet 2 H. H. RANNEY ET AL CAM MECHANISM FOR VARIABLE LENGTHTHROW .Fil ed Feb. 18, 1948 Jan. 3, 1950 Patented Jan. 3, 1950 2,493,420CAM MECHANISM FOR VARIABLE LENGTH THR Herbert H. Ranney and Roger W.Brown, Windsor, Vt., assignors to Cone Automatic Machine Company Inc.,Windsor, Vt., a corporation of Vermont Application February 18, 1948.Serial No. 9,253

This invention relates to cam mechanism and more particularly to suchmechanism particularly adapted to actuate a tool slide or carriage, andit has for an object to provide such a mechanism readily adjustable toproduce selectively motion of either of a pair of amplitudes. This isparticularly advantageous in the actuation of tool slides to provide foroperation on work pieces which differ substantially in length as itmakes possible the changing of the stroke without requiring removal andreplacement of actuating cams.

With a single barrel type of cam acting upon a follower the motionobtainable for a small rtation of the cam is limited by the acceptablepressure angle of contact against the follower by the cam. This is areal and limiting factor in cam design when it is desirable to produce amultiplicity of actions in 360 of drum rotation.

This invention has for a further object, therefore, to providemechanical means making possible a greater axial carriage movement froma small rotation of cam drums arranged in complementary action thanwould be possible with a single cam drum operating at an equal angle ofpressure.

For a complete understanding of this invention, reference may be had tothe accompanying drawings in which Figure 1 is an exploded perspectiveview of certain of the cam mechanism parts.

Figures 2 and 3 are fragmentary top plan views showing the mechanismapplied to the cam shaft of a multiple spindle lathe of well known type,the parts being arranged for short and long strokes of the toolcarriage, respectively.

Figure 4 is a central longitudinal sectional View through the cammechanism adjusted for short throw and with the follower carriage shownin full and dotted lines at its limits of throw.

Figure 5 is a view similar to Figure 4, but showing the followercarriage in full lines at the opposite limit of its throw.

Figure 6 is a view similar to Figure 4, but with the parts adjusted toproduce a long throw, the extent of throw of the carriage being shown infull and dotted lines.

Figure '7 is a detail sectional view on line I-'| of Figure 4.

Figure 8 is a detail sectional view on line 88 of Figure 5.

Referring to the drawings, at I' is shown a rotary shaft mounted insuitable stationary bearings, one of which is indicated at 2. Thisshaft, as shown, is the cam shaft of a multiple 5 Claims. (01. 74-57)spindle lathe of the well known Cone type, this cam shaft, as is wellknown in the art, carrying along its length various cam-carrying drumsfor actuating various parts of the machine and determining the cycle ofoperations. At 3 in Figures 4, 5, 6 and 8 is shown a portion of a toolslide or carriage arranged to be moved lengthwise of the axis of the camshaft, this slide carrying various end working tools for operating onwork carried by a plurality of rotary spindles arranged in circulararray in an indexing carrier (not shown) arranged parallel to the axisof the cam shaft I. This carriage 3 carries a cam follower 4 which ridesin a cam path 5 on a drum 6. As shown one or both sides of the cam pathmay be formed by curved cam plates 1 which may be bolted to theperiphery of the drum 6 as by the bolts 8 (see Figures 2 and 3). The camdrum 6 is fixed to a sleeve I I3 keyed to a sleeve I I; which, in turn,is pinned to the shaft l as by the taper pin I2. The drum 6 is thusmounted for axial motion along the shaft I, but is held against relativeangular motion with respect thereto.

A second cam drum I5 is also carried by the shaft I but this cam drum I5is journaled for rotation thereon but is heldagainst axial motion. Themeans for retaining it in axially fixed position comprises a smalldiameter extension l6 which is journaled within a bushing IT in thebearing 2, and which carries threaded on its outer end an adjusting nutI8 bearing against a washer I9 engaging the outer end of the bushing IT.A second washer 2!! is interposed between the drum l5 and the bearingbushing I1. The drum I5 is thus held against axial motion relative tothe shaft I by being so held with reference to the bearing 2.

The drums 6 and I5 have their adjacent ends in telescopic relation, thedrum 15 being of smaller external diameter than the interior diameter ofthe drum 6, the adjacent end ,of which is formed tubular. The drums 6and I5 are connected together by cam mechanism so that by relativerotation of these drums, the drum Bmay be given an axial motion relativeto the shaft I. As shown this cam mechanism comprises an internal campath 22 on the inner face of the drum I5 and which may be formed by camplates 23 on opposite sides secured to the inside face of the drum 6 asby the bolts 24. Riding in this cam path is a follower roll 21 journaledon a pin 28 fixed in the cam drum I5. With this construction it will beevident that relative rotation of the cam drums 6 and I5 will cause thecam drum 6 to be moved forwardly and backwardly axially as the follower2? rides in the cam groove 22.

Means are provided by which, at will, the cam drum 15 may be heldstationary during the rotation of the shaft I so that as the shaft l isrotated, the cam drum 6 will be rotated relative to the cam drum l5 andthus be given in addition to its rotary motion, the axial motionproduced by the traverse of the cam groove 22 by the follower 21, or ifdesired, the cam drums l5 and 6 may be locked together for simultaneousrotation, in which event there is no relative rotation between these twodrums so that they rotate as a unit and there is no axial motion of thecam drum 6. This means comprises an arcuate key 30 having a keyprojection 3|. This key 30 may be fixed in the position shown in Figure2 to the cam drum I5, as by screws 32, with the key projection 3|engaging in a slot 33 in the adjacent end of the drum 6, as, forexample, cut in the edge of one of the cam plates 23. The throw of thecarriage is thus produced entirely by the throw of the external cam path5, the total throw being then shown by the full and dotted linepositions of the follower 5 shown in Figure 4. This key 30 may removedfrom this position, reversed end for end, and secured to the cam drum 15adjacent to its outer end close to the fixed bearing 2, this position ofthe parts being shown in Figure 3, the screws 32 being then engaged inthe holes 35 of the drum 15. In this position of the parts, the keyprojection 31 engages in a slot 36 in the upper face of the hearing 2.With this arrangement the drum I5 is held against rotation with theshaft I, so that as the shaft 1 rotates and rotates the drum 6, the drum6 is caused to move axially because of its cam connection with the druml5, this cam connection now being operative. The result is that thethrow of the carriage 3 is increased to the summation of the throw dueto the shape of the external cam path 5 and the internal cam path 22,the extent of this throw being shown by the full and dotted linepositions of the carriage 3 shown in Figure 6.

From the foregoing description of an embodiment of this invention itwill be evident to those skilled in the art that various changes andmodifications might be made without departing from the spirit or scopeof this invention.

We claim:

1.In combination, a rotary shaft, a pair of cam elements arrangedconcentrically on said shaft, one of said elements having a cam path andthe other of said elements having a follower riding in said path, afixed member adjacent to one of said elements, means for selectivelycoupling said one element to said member or to said other element, saidother element being keyed to rotate with said shaft and having a drivingcam path, and a follower engaging in said driving cam path.

2. In combination, a rotary shaft, a carriage movable parallel to saidshaft, a follower carried ,4 by said carriage, a pair of cam elements onsaid shaft one having a cam path for cooperation with said follower andbeing keyed for motion axially relative to said shaft, the other of saidcam elements being journaled on said shaft and having cam and followerconnection to said one cam element a fixed member and means forselectively coupling the other of said cam elements to said one elementto rotate therewith or for securing said other cam element to said fixedmember.

3. In combination with a rotary shaft, a pair of cam drums on saidshaft, one of said drums being movable axially relative to said shaftand keyed against rotation with respect thereto, a carriage movablelengthwise of said shaft, a cam follower on said carriage, a cam path onsaid one drum cooperating with said follower whereby rotation of saidone drum moves said carriage, said drums having cooperating cam andfollower mechanism causing motion of said one drum axially of said shafton relative rotation between said drums, a fixed member and means forselectively coupling said other drum to said one drum to rotatetherewith or for securing said other drum to said fixed member.

4. In combination, a rotary shaft, a pair of drums mounted on said shaftone for axial and nonrctary motion relative to said shaft, and the otherfor relative rotation and axially fixed with reference to said shaft,one of said drums being telescopically related to the other of saiddrums and having cam and follower connections therewith caosing arelative rotation of said drums to move said one drum axially, said onedrum having a peripheral cam path, a movable carriage, a follower onsaid carriage engageable with said cam, a fixed member and means forselectively coupling said drums together for simultaneous rotation orfor holding said rotarily mounted drum to said fixed member againstrotation.

-5. In combination, a rotary shaft, a pair of telescopically relateddrums carried by said shaft,

one of said drums being keyed for rotation and axially movable on saidshaft, the other of said drums being ,journaled on said shaft andretained against axial motion, the outer of said drums having aninternal cam path and the inner of said drums having a follower engagingin said cam path, whereby relative rotation between said drums causesaxial motion of said axially movable drum, said outer drum having anexternal cam path, a carriage movable lengthwise of the axis of saidshaft and having a follower engageable in said external cam path, afixed member adjacent to one end of said journaled drum, and key meansfor selectively connecting said drums together for simultaneous rotationor for coupling said journaled drum to said fixed member.

HERBERT H. R-ANNEY. ROGER W. BROWN.

No references cited.

